It is critical in today's communication systems to provide and maintain the integrity of data communication networks even during line failures and module failures. A link failure may impact a large amount of data traffic and may cause many transmissions to be interrupted. Failures, which can be frequent and almost impossible to avoid, may be caused by human error or inclement weather. Accordingly, optimized protection signaling systems and methods are desired in order to quickly re-establish network communications once failures have been detected.
A line failure may result from damage to physical fibers and optical components, such as the malfunction of amplification equipment situated along the optical data path. Module failures may consist of errors in the transmission or reception equipment. Both line failures and module failures may disable the network segment or link between two adjacent nodes, forcing the connection off its original home path. It is, therefore, desirable in today's telecommunication network systems to provide rerouting and restoration techniques to reroute the interrupted traffic, and once the failure is repaired, restore the traffic to its original home path.
Link restoration methods may include handling a link failure by calculating a backup path and rerouting the traffic on the backup path, even though the calculated backup path may not be the most efficient path to reroute the traffic. While on the backup path, the connection may use bandwidth resources that are reserved for another connection, which may be undesirable given that the backup path may be the home path of another connection. Using the home path resources of the other connection may prevent the other connection from returning to its home path, which is undesirable, given that the home path may be an optimal and efficient calculated path for the other connection.
In a control plane enabled network, a subnetwork connection (“SNC”) may move off a home/nominal path. The SNC may move off the path due to, for example, a mesh restoration or a maintenance action. When the SNC moves off the path, the path resources may be released and made available for other connections to utilize. Other times, the path resources may be strictly held and may not be available for other connections to utilize.
When path resources associated with an SNC are released, another connection may take the home/nominal path of the SNC when, for example, the SNC is first being provisioned or when the SNC is restored. This may prevent an SNC from returning to its home path after, for example, the link is repaired, or the maintenance action is completed. On the other hand, when the path resources are strictly held, this may cause a reduction in an overall availability of restoration bandwidth, as the bandwidth is being held by the connection even when the connection is not on that path. Further, the bandwidth that is being held is advertised as unavailable for utilization by new SNCs. The standard network bandwidth advertisement does not explicitly identify whether a link is up or down and advertises how much bandwidth is available. For example, when a link is down, the advertisement may indicate ‘0’ bandwidth available. The advertisement may not state details, such as whether the link is up but fully occupied or whether the link is down. This may make it difficult to know when an SNC that is on a restoration path may return to its home path. The advertisement may not help in determining when the connection can be reverted back to its home/working path.
It is desirable to have a method and system to retain a connection's home path resources and restore the connection to its home path once a link failure has been repaired.